An operating system is a computer program that is executed by one or more processors. The purpose of an operating system is to control the utilization of resources in a computer system. An operating system generally includes various functional modules, each of which is implemented as an instruction sequence that can be executed by the one or more processors. Each such functional module, when executed by the processor, minimally causes the processor to perform some function integral to the operating system.
An operating system typically includes functional modules for performing various activities including, but not limited to allocating processing resources to a task, controlling peripheral devices communicatively coupled to one or more processors and storage and retrieval of information using files. Files are typically managed by an operating system by controlling the placement of information on computer readable medium.
An operating system is typically developed using well-known methods for the development of software. Using existing software development methods, functional modules are independently tested against requirements specifications. Once the individual functional modules are tested, they are integrated together to form a complete operating system. The complete operating system is then tested to ensure proper operation.
During development, the various individual functional modules undergo testing at various levels. For example, in the early stages of development a functional module may include event descriptions. When a particular event is detected in a functional module, the record is typically made of the event. The event record of this type is useful in identifying anomalies that may be present in the design of a functional module. Once a particular functional module is fully tested and subsequently validated, common wisdom dictates that event descriptions included in the functional module for the purposes of identifying anomalies are no longer necessary. As such, an event description included in a functional module represents superfluous code.
Even after a particular functional module has been validated, additional anomalous conditions may eventually arise. For example, a particular functional module may not be exhaustively validated against a set of functional requirements. In this case, a validated functional module may behave erratically when it is subject to a particular use scenario. In this situation, there is little hope in identifying the cause of an anomaly because the event descriptions used to identify anomalous behavior in the functional module are eliminated prior to the creation of production software images that comprise the operating system.